An instrument for measuring the intensity and dose of cancerigenic ultraviolet radiation

An instrument for measuring the intensity and dose of cancerigenic radiation from the Sun and artificial sources has been developed. A 4H-SiC Schottky barrier photodetector is used as the sensor. The sensitivity spectrum of the photoelectric transducer lies in the region 240–300 nm and has a maximum at 260 nm. The quantum efficiency is ≈0.3 electrons/photon (at λ = 254 nm), and its temperature coefficient at T = 250–310 K is < 0.1%/°C. The dimensions of the device are 3 × 6 × 11 cm.     

Multichannel linear detector for x-ray spectroscopy

This paper considers a new linear multichannel x-ray detector designed on the basis of a BLPP-369M4 silicon photodiode array (2612 photodiodes, array pitch 12.5 µm, height 4 mm, and dynamic range 10⁴). The structure and characteristics of the multichannel detector are given, along with the Kα1,2, Kβ ₁, and Kβ ₅ x-ray emission lines and a K-edge absorption spectrum of metallic copper recorded on a universal URS-2I spectrometer using this detector. The resolution and the signal/noise ratio of these spectra are superior to those of spectra recorded by an SRPP-21 gas ionization counter at the same recording time. The detector has a spatial resolution of 20 µm and an x-ray detection limit to equal 1 quantum at λ = 1.54 Å. It is suitable for studying the fine structure of absorption spectra at 1–10 Å.     

A system and methodologies for absolute quantum efficiency measurements from the vacuum ultraviolet through the near infrared

In this paper we present our system design and methodology for making absolute quantum efficiency (QE) measurements through the vacuum ultraviolet (VUV) and verify the system with delta-doped silicon CCDs. Delta-doped detectors provide an excellent platform to validate measurements through the VUV due to their enhanced UV response. The requirements for measuring QE through the VUV are more strenuous than measurements in the near UV and necessitate, among other things, the use of a vacuum monochromator, good dewar chamber vacuum to prevent on-chip condensation, and more stringent handling requirements.     

A device for measuring the density and surface tension of melts

A method was developed and an experimental device was constructed for measuring the density and surface tension of melts. The hydrostatic method was used with the application of a volute-spring balance, which significantly simplified the device design. Its operation was tested by measuring the density and surface tension of a LiF melt in a temperature range of 1160–1350 K. The measurement errors are 1.5–2% and 10%, respectively.     

A nanosecond optical parametric oscillator in the mid-IR region with double-pass pump

An optical parametric oscillator (OPO) with double-pass pump based on MgO:PPLN and PPLN periodic structures is described. A compact nanosecond Nd:YLF laser has been used as a pump source at 1.053 μm (the pumping pulse duration is 5–7 ns at a maximum pulse energy of 300 μJ at frequencies of 1–7 kHz). The oscillation threshold of the OPO based on MgO:PPLN was varied in a range of 11–28 μJ at wavelength of 2.1–4.3 μm. The conversion efficiency from the pump wave to an idler wave decreased from 8.6 to 2.5% in the range of 2.0–4.3 μm. For PPLN-OPO the measured threshold was 36 μJ at 4.2 μm and 49 μJ at 4.7 μm. The conversion efficiency of the pump energy into the energy of an idler wave was 3.3μ-0.4% at wavelengths of 4.2–4.7 μm.     

Mobile laser meter of hydrosphere pressure variations

A device for measuring hydrosphere pressure variations at depths of down to 1000 m in the frequency range of 0–1000 Hz with an accuracy of 10–30 mPa is described.     

A setup for measuring the temperature dependence of the refractive indices of solids

A setup for measuring the temperature dependences of refractive indices n(T) of semiconductors and dielectrics in the temperature range 300–700 K at the wavelengths of a He—Ne laser λ=0.63, 1.15, and 3.39 μm is described. Samples in the form of plane—parallel plates serve as Fabry—Perot etalons the optical thickness of which depends on the temperature. Upon heating and subsequent cooling of a sample, interference oscillations of the refiected-light intensity are recorded and used to determine the dependence n(T). The values of the refractive index at room temperature and the thermal expansion coefficient used in calculations are taken from the literature. Comparing the interferograms obtained for a heated and cooled sample allows evaluation of the temperature difference between the sample’s probed area and a measuring thermocouple. The relative error in determining thermooptical coefficient dn/dT in the range 300–700 K is within 1%.     

Spectrophotometric method for measuring the groove depth of calibration reflection gratings

A method for measuring the groove depth of calibration gratings is proposed which is based on measuring the spectral dependence of the the zero-order reflection diffraction efficiency. The errors of the method are determined by three main factors: the shift of the maxima of the spectrum due to the wall slope of the grating grooves, the error in setting the wavelength of the spectrophotometer, and the divergence of the light beam in the setup. It is shown theoretically that the measurement error is in the range of 0.25–1%, depending on the fabrication technology of the grating and measuring equipment. The method was tested experimentally using commercial calibration gratings. The range of applicability of the method is discussed in terms of the geometrical parameters of the microstructure of reflection gratings and the characteristics of the spectrophotometer used.     

A remotely operated broadband photodiode current preamplifier

A remotely-operated broadband photodiode current preamplifier with a secondary power source is described. The preamplifier ensures measurements of small currents (∼100 nA) in a 1-kHz to 15.6-MHz band (when the photodiode capacitance value is up to 100 pF). Its gain is regulated remotely. The shape of a signal from the preamplifier is digitized by a 12-bit analog-to-digital converter placed on the computer PCI bus. The designed setup is intended for measuring the time spectra of fast optical processes. The preamplifier can be used for solving many other physical problems, where it is necessary to remotely regulate the recording-channel gains.     

Test investigation on hydraulic losses in the discharge passage of an axial-flow pump

In a discharge passage with a guide blade discharge circulation and secondary flow because of bend pipe, the flow in a 1-channel discharge passage of an axial flow pump is a complicated spiral flow. For a 2-channel passage, the discharge in the left channel is bigger than that in the right, and the passage hydraulic losses are abnormal. In this study, the section current energy of the passage is accurately measured and determined with a 5-hole probe. The hydraulic loss characteristics are determined and analyzed. The methods deducing the hydraulic losses are investigated. The results indicate that the passage hydraulic losses are not proportional to the flow discharge. Compared with a circular pipe, the hydraulic losses of a divergent discharge passage are smaller and the pump assembly efficiency is 10%–30% higher. As for the 1-channel passage, the axial-flow pump outlet circulation is usually too big; the passage hydraulic losses are also big, but a small circulation can slightly reduce hydraulic losses. As for the 2-channel passage, discharges in the two channels are not equal and the hydraulic losses increase. The outlet guide blade with a small discharge circulation or without circulation could reduce discharge passage hydraulic losses and increase pump assembly efficiency by 6%–11%. __________ Translated from Chinese Journal of Mechanical Engineering, 2006, 42(5): 39–44 [译自: 机械工程学报]     

A new method for charged particles identification with a CsI(Tl) crystal

A spectrometer for detecting and identifying light charged particles with low energies (>∼1 MeV) is described. The spectrometer consists of a thin CsI(Tl) crystal, an ФЭУ-176 photomultiplier, and a waveform digitizer. Digital oscillograms of anode pulses are stored and analyzed in off-line processing. In order to reconstruct the energy and specific energy losses, the two-component character of the scintillation fluorescence decay in a CsI(Tl) crystal and the dependence of the fast component on the specific loss value are used. A digital particle identification method is proposed. The results of experimental studies of the CsI(Tl) crystal scintillation properties and efficiency in identifying electrons, protons, and α-particles in an energy range of ∼1–10 MeV are presented. It is shown that the efficiency of the digital method for proton and α-particle identification is 1.5–2 times higher than that of the known analog methods.     

Relative detection efficiency of back- and front-illuminated charge-coupled device cameras for X-rays between 1 keV and 18 keV

High-resolution x-ray measurements were performed with a von Hamos-type bent crystal spectrometer using for the detection of the diffracted photons either a back-illuminated charge-coupled device (CCD) camera or a front-illuminated one. For each CCD the main x-ray emission lines (e.g., Kalpha, Kbeta, Lalpha, and Lbeta) of a variety of elements were measured in order to probe the performances of the two detectors between 1 and 18 keV. From the observed x-ray lines the linearity of the energy response, the noise level, the energy resolution, and the quantum efficiency ratio of the two CCDs were determined.     

Highly efficient extraction of a proton beam by using bent single crystals

A substantially increased beam extraction efficiency can be achieved in the case of a multiple beam’s passage through a crystal. This suggestion was verified in experiments with short (5–7 mm long) curved single crystal with bending angles of 1.5–1.7 mrad performed at the Institute of High Energy Physics. The peak effiency values obtained were 47±3%, and the maximum average efficiency was 42±2% for a 23% intensity taken from an accelerated beam. The maximum extracted beam intensity was 6×10¹¹ protons per cycle.     

Energy dependence of the relative light output of YAlO<Subscript>3</Subscript>:Ce,Y<Subscript>2</Subscript>SiO<Subscript>5</Subscript>:Ce,and YPO<Subscript>4</Subscript>:Ce scintillators

The nonlinear dependence of the relative light output on the energy deposited in single-crystal scintillation materials YAlO₃:Ce (YAP:Ce), Y₂SiO₅:Ce (YSO:Ce), and YPO₄:Ce (YPO:Ce) has been studied. The investigations have been conducted under quasi-monochromatic X-ray excitation in the energy range of 9.5–100 keV. In addition to the standard technique for measuring the nonproportional scintillator response based on the dependence of the full-energy peak position on the energy of incident radiation, a method is proposed for measuring the light output by X-ray fluorescence peaks. Using this method for YAP:Ce, it is possible to investigate the nonlinear dependence of the light output on the photon energy in the energy range of 2–40 keV. Along with this method, the K-dip spectroscopy method has been proposed and tested by measuring the dependence of the relative light output on the electron energy in the range of 0.1–80.0 keV. The processes resulting in the loss of the scintillation material efficiency at a high ionization density are considered.     

Condensation heat transfer coefficients of HCFC22, R410A,R407C and HFC134a at various temperatures on a plain horizontal tube

In this study, external condensation heat transfer coefficients (HTCs) of HCFC22, R410A, R407C, and HFC134a were measured on a smooth horizontal tube at 30, 39, and 50°C with the wall subcooling of 3–8°C. The results showed that condensation HTCs decreased for all fluids tested with an increase in temperature. This is due mainly to such properties as the saturated liquid density and liquid thermal conductivity. These properties decrease as the temperature increase and accordingly HTCs decrease. The condensation HTCs of R410A are 9.2–19.7% higher than those of HCFC22 while those of R134a are 2.5–10.2% lower than those of HCFC22. Condensation HTCs of R407C, non-azeotropic mixture, are 29.4–34.3% lower than those of HCFC22. Overall, the HTCs of R407C are much lower than those of HCFC22, HFC134a and R410A due to the mass transfer resistance in a diffusion vapor film. Condensation HTCs of HCFC22 and HFC134a are higher than those calculated by Nusselt’s equation by 7.7–11.8% and 4.0–11.1% respectively. On the other hand, HTCs of R407C measured on plain tube, however, are not well predicted by these well-known prediction correlations due to the introduction of mass transfer resistance associated with non-azeotropic mixtures.     

纳秒激光等离子体光源的光谱测量技术

提出了一种新的探测和测量激光等离子体软X射线源光谱强度的方法。此方法使用通道电子倍增器和定标过的硅光电二极管为探测器,前者是非标准探测器,后者为标准探测器。应用电荷灵敏前置放大器和峰值探测器测量探测器产生的电量,并以高分辨率的光谱仪为分光元件,在已知光栅效率、通道电子倍增器增益、硅光电二极管能量响应的条件下,给出了计算激光等离子体软X射线源在某一波长光谱强度的公式。     

Measurements of the zone sensitivity characteristics of photocathodes of fast ϕεy-143 and ϕεy-174 photomultipliers

The results of measurements of zone sensitivity characteristics for photocathodes of fast ϕεy-143 and ϕεy-174 photomultipliers and their spectral sensitivity in a wavelength range of 400–700 nm are presented. An automated setup for measuring photocathode zone characteristics is described.     

A parallel plate avalanche detector for low energy ion identification

A setup for identifying low-energy (1–10 MeV) ions with charges Z ≥ 1 by simultaneously measuring the energy losses and the time of flight is described. The setup is composed of a multiwire proportional chamber and a strip silicon detector, which are used to measure the ion energy, and two low-pressure avalanche wireless detectors for measuring the energy losses and the time of flight. Results obtained in measuring α particles from ²²⁶Ra source and p, Be, C, and O ions produced on the ITs-100 cyclotron at the Flerov Laboratory of Nuclear Reactions are presented.     

Recording the energy spectrum and time characteristics of laser-plasma electrons

The design of small spectrometers of laser-plasma electrons with energies in the range 1–1000 keV is described. A technique for calibrating spectrometers is presented. The results of measuring an electron spectrum in a laser experiment performed with these spectrometers are presented.     

A grazing incidence spectrograph for recording spectra in the range of 5–50 nm

A wide-range grazing-incidence spectrograph based on a spherical grating has been developed for recording integrated (over time) line spectra in the region of 5–50 nm. Resolution of the spectrograph λ/Δλ has been determined; at a wavelength of 5 nm, it exceeds 500 units. The spectrograph has been used to analyze line spectra of multiply charged ions for strong resonance lines in the range of 15–20 nm and record the line of X-ray lasing on the 3p-3s transition of a Ne-like Ar ion with wavelength λ = 46.9 nm.